| Summary: | Information about the current condition of the migrant shorebirds in a sector of the estuary, adjacent to Rio Gallegos city, which is subject to diverse changes resulting from the urban use, is presented. From March 2011 to January 2012, 52 visits to 5 sampling stations were performed, going along transects perpendicular to the coast. The specific diversity was higher in spring, exceeding by more than twice the rest of the seasons. From the comparative analysis between the obtained results and previous studies, it arose that the specific richness did not present any changes, staying between 8/9 species. The most notorious changes in the community, nevertheless, appeared in the maximum abundance by species and habitat use, except for the Magellanic Oystercatcher, that maintained its abundance, resulting dominant (Occurrence Frequency= 92%). The rest of the species drastically reduced the use of the area, like the White-rumped Sandpiper (99%), the Hudsonian Godwit (96.3%), and the Red Knot (97.4%), in relation to the historical records of 1997/99. The most used habitats were the clay silt substratum and the sandy substratum, while the marshland was used the least, in spite of previous existing reports of frequent use by several species. The possible causes of these changes are discussed, and recommendations are made, like the need to keep an assortment of different kinds of habitats, the structure of the substratum, and the Urban Coastal Reserve, being necessary the planning and prior study before any anthropic action that modifies the natural erosive-sedimentary balance of these fragile ecosystems. Diversidad, abundancia estacional y uso de hábitat de aves playeras migratorias en el estuario del rio Gallegos (Santa Cruz). Se presenta información sobre la condición actual de las aves playeras migratorias en un sector del estuario, adyacente a la ciudad de Río Gallegos, que está sujeto a diversos cambios provenientes del uso urbano. Desde marzo de 2011 a enero de 2012, se realizaron 52 visitas a 5 estaciones de ...
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